Infiltrator: The Cheapest Way to Install a Long-Lasting Septic Leach Field System. No Rock Required

The old-fashioned way of installing a septic leach field system was to connect your house or building to an underground septic tank, and to connect the septic tank to a bed of crushed rock or stone to diffuse the effluent overflow safely into the groundwater.

The problem with this traditional method is that 1) rock is expensive and difficult to install, 2) the system can easily back up because the holes between the rock tend to plug 3) it is recommended that the system be cleaned up and replaced every so often to avoid backflow 4) the heavy equipment it takes to install can destroy landscaping or crack the septic tank itself in the event that the tank is driven over while buried.

Fortunately, a company called Infiltrator systems has patented a system called the Infiltrator Leach Field Chamber Systems. These systems are comprised of 4´ long half-domes made out of durable polyethylene plastic. The design allows for maximum space for the effluent to diffuse, making them more difficult to clog. They also rarely, if ever, have to be replaced, and maintenance is simple. The chambers are inexpensive compared to purchasing enough stone to cover a traditional leach field, and they can be connected in such as way as to create a smaller overall footprint requirement of the field itself. The best part about this system is that the Infiltrator chambers are so lightweight that a child can pick them up. The ease of handling can further reduce the cost of installation.

Here is how to install an Infiltrator leach field system:

Step 1: Survey the site. Make sure you have selected a proper sitefor your septic tank and system. This is very important; choosing the wrong place for your system can result in the necessity for expensive cleanup. Also, check your state and local regulations about septic system install, and get permits when necessary.

Optional: to save space in your leach field, plan for parallel trenches and use a distribution box to split the effluent equally for best dissipation.

Step 2: Make sure you have proper fittings and equipment. The standard fitting size for septic systems is a 4″ diameter PVC pipe. Infiltrator systems and most septic tanks are already outfitted with the right sized inlets and outlets, but additional work may be necessary. The manufacturer suggests you have the following:

• Enough chambers to facilitate the size of your tank and home/building

• Multiport end caps

• PVC pipe and couplings

• Backhoe

• Level

• Shovel and rake

• Tape measure

• Hole Saw

• Distribution box (optional)

• 2 inch drywall screws (optional)

• Screw gun (optional)

• Small valve-cover box (optional)

• 4″ cap for inspection port (optional)

Step 3: Dig the trenches. First, stake out the site and set the elevations of the tank and trench bottom. Second, set up measures such as berms and tarps to avoid erosion during the installation process in the event of rainfall. Third, dig out 3´ wide trenches and make sure they are level. Trenches should be at least 28″ deep but no more than 8´ deep. Finally, rake the bottom and sides of the trench by hand to clear out rocks and debris.

Note: Avoid walking inside the trench. Compacting the soil will hinder effluent dissipation. Also, avoid driving over the chambers. If you must, drive over them after they are installed and are covered with compacted soil. Never drive over them length-wise, only width-wise. With a 12″ minimum compacted soil cover the chambers can support a wheel load rating of 16,000 lbs/axle, which is equivalent to an H-10 rating.

Step 4: Prepare the end cap. Follow the manufacturer instructions to carefully remove the plastic seal on the end-cap with a utility knife so it can be snugly fitted with PCV pipe inlet.

Step 5: Installation. Set the PVC inlet at 11.5″ from the bottom of the trench. Connect the inlet pipe to the end cap you prepared above, and put the end cap into the base of the trench. Set the first chamber over the back edge of the end cap. Lock subsequent chambers in place by holding them at a 45 degree angle to the previous one, aligning them with the connector hook, and setting the locking pin in place before lowering the chamber into the trench. You can swivel the chambers on the axis of the locking pin to accommodate slight curvature in the trench. Verify all chambers are level. The last chamber in the trench requires an end cap. Install this end cap at a 45 degree angle like the other chambers and do not remove the plastic seal as you did with the first inlet cap.

Optional: Install inspection ports along the top of the chambers to aid in maintenance. See manufacturer instructions for details.

Step 6: Bury the chambers. Start by using a shovel to fill the sidewall areas at the joints where the chambers connect. Keep filling the sidewall area until there is enough soil to pack down by foot. Walk along the edges of the trench to compact the soil – this is very important to maintaining structural integrity (do not do this in wet or clay soils).

Note from the manufacturer: “Before backfilling, the system must be inspected by a health officer or other official as required by State and local codes. Create an as-built drawing at this time for future records.”

Continue backfilling the trench until it is covered with at least 12″ of soil, and then mound another few inches of soil to make up for settling and erosion. After burial is complete, the soil should be compacted by foot (not vehicle) and planted with groundcover to further prevent erosion.

For further questions or information about Infiltrator Septic Leach Field Systems, please contact Loomis Tank Centers at (800) 549-5514.